Patent application title: Push-in wire connector with improved busbar

Abstract:

A push-in wire connector has an improved busbar suitable for use with
either solid or stranded wire. The connector has a housing with a hollow
interior. At least two openings in the housing provide access to the
interior for the ends of wires inserted into the connector. A busbar is
mounted in the housing. The busbar defines at least two wire-crossing
axes extending from an entry edge to an exit edge and a thickness between
a top face and a bottom face. The busbar has a wire-receiving pocket
extending below the top face on each of the wire-crossing axes and a
wire-engaging protrusion extending above the top face on each of the
wire-crossing axes.

Claims:

1. A push-in wire connector, comprising:a housing having a hollow interior
and at least two openings providing access to the interior for the ends
of wires inserted into the connector;a busbar mounted in the interior of
the housing, the busbar defining a thickness between a top face and a
bottom face, the busbar also defining an entry edge, an exit edge, and at
least two wire-crossing axes extending from the entry edge to the exit
edge;the busbar having a wire-receiving pocket extending below the top
face on each of the wire-crossing axes and a wire-engaging protrusion
extending above the top face on each of the wire-crossing axes.

4. The push-in connector of claim 1 wherein the wire-engaging protrusion
is coined in the busbar.

5. The push-in connector of claim 1 further comprising a spring member
mounted in the housing.

6. The push-in connector of claim 5 wherein the spring member includes at
least two spring fingers each having a free end, one spring finger being
aligned with each crossing axis, and the busbar is disposed such that
prior to insertion of a wire the free ends of the spring fingers lies at
least partially in a wire-receiving pocket.

7. The push-in connector of claim 1 wherein the wire-receiving pocket has
a depth below the top face of at least about 50% of the thickness of the
busbar.

8. The push-in connector of claim 7 wherein the wire-receiving pocket has
a length of at least about 30% of the distance between the entry edge and
the exit edge of the busbar.

9. The push-in connector of claim 1 wherein the wire-engaging protrusion
has a height above the top face of at least about 40% of the thickness of
the busbar.

10. The push-in connector of claim 9 wherein the wire-engaging protrusion
has a length of at least about 50% of the distance between the entry edge
and the exit edge of the baseplate.

11. A push-in wire connector, comprising:a housing having a hollow
interior and at least two openings providing access to the interior for
the ends of wires inserted into the connector;a busbar mounted in the
interior of the housing, the busbar defining a thickness between a top
face and a bottom face, the busbar also defining an entry edge, an exit
edge, and at least two wire-crossing axes extending from the entry edge
to the exit edge;the busbar having a wire-receiving pocket extending
below the top face on each of the wire-crossing axes, the wire-receiving
pocket having a depth of at least about 50% of the thickness of the
busbar.

12. The push-in connector of claim 11 wherein the wire-receiving pocket
has a length of at least about 30% of the distance between the entry edge
and the exit edge of the busbar

14. The push-in connector of claim 11 further comprising a spring member
mounted in the housing.

15. The push-in connector of claim 14 wherein the spring member includes
at least two spring fingers each having a free end, one spring finger
being aligned with each crossing axis, and the busbar is disposed such
that prior to insertion of a wire the free ends of the spring fingers
lies at least partially in a wire-receiving pocket.

16. A push-in wire connector, comprising:a housing having a hollow
interior and at least two openings providing access to the interior for
the ends of wires inserted into the connector;a busbar mounted in the
interior of the housing, the busbar defining a thickness between a top
face and a bottom face, the busbar also defining an entry edge, an exit
edge, and at least two wire-crossing axes extending from the entry edge
to the exit edge;the busbar having a wire-engaging protrusion extending
above the top face on each of the wire-crossing axes, the wire-engaging
protrusion having a height above the top face of at least about 40% of
the thickness of the busbar.

17. The push-in connector of claim 16 wherein the wire-engaging protrusion
has a length of at least about 50% of the distance between the entry edge
and the exit edge of the baseplate.

Description:

BACKGROUND OF THE INVENTION

[0001]This invention relates to push-in wire connectors. Push-in
connectors operate, as the name implies, by simply pushing a stripped end
of two or more wires or conductors into the connector. Once the wires are
pushed into the connector no closing, crimping, twisting, insulation
displacement or other manipulation of the connector is required to finish
the connection, making the push-in connector advantageous from the
standpoint of time needed to install it. The push-in connector must
perform several tasks including electrically isolating its conductors
from the surrounding environment, retaining the conductors in the
connector, and providing good electrical conductivity between the
conductors.

[0002]The electrical isolation function is typically performed by a
housing made of electrically insulating material. The housing has a
generally hollow interior. Openings in the housing provide access to the
interior for the stripped ends of two or more electrical conductors. Once
inside the housing the bared ends of the conductors are fully surrounded
by the insulating housing.

[0003]The function of providing electrical conductivity is performed by an
electrically-conductive shorting member. The shorting member, often
called a busbar, is inside the housing and is disposed so as to be
engageable with all conductors inserted into the housing. The shorting
member provides a conductive path between all inserted conductors. Since
the primary job of the busbar is conduction, it is typically made of a
highly conductive material such as copper or tin-plated copper. But even
a highly conductive busbar will not provide good conductivity between
conductors if those conductors are not held firmly in contact with the
busbar. Thus it is common to include a spring member which works in
concert with the busbar to hold the conductors firmly against the busbar.
Various arrangements of the spring member are possible, including
building it into the housing, building it into the busbar, or making it a
separate component in the interior of the housing. In any case, the
spring member urges all conductors into solid mechanical and electrical
engagement with the shorting member.

[0004]The function of holding the conductors in the housing is performed
by a retention member that engages the ends of the inserted conductors
and prevents axial retraction from the housing. As in the case of the
spring member, the retention member could be built into the housing.
Alternately, the retention member and spring member can be configured as
a combined unit inside the housing. In either case the retention member
grasps the conductors and prevents unintentional removal of the
conductors from the housing. In some embodiments the retention member is
releasable so that conductors may be selectively removed from the housing
without damage to any of the components. In other embodiments where it is
desired that the conductors not be removed from the connector under any
circumstances the retention member is intentionally made to be
non-releasable.

[0005]As just mentioned, the retention member is often configured in
combination with the spring member to apply a force that urges the
inserted conductor into contact with the shorting member and prevents
retraction of the conductor. A common configuration is to have a
resilient metal retention member having spring fingers formed therein. As
a conductor is inserted into the housing it engages a spring finger and
causes it to flex away from its rest position. The resulting deflection
of the spring finger generates a compressive force on the conductor that
presses it into solid contact with the busbar. The spring fingered is
angled to permit insertion of the conductor past the finger in one
direction but withdrawal of the conductor in the opposite direction is
not permitted due to the self-locking configuration of the spring finger.
Thus, engagement of the spring finger with the conductor provides the
dual functions of pressing the conductor into the busbar and preventing
withdrawal of the conductor from the housing.

[0006]The pressing of the conductor into the busbar, of course, requires a
stable structure for resisting the compressive force of the spring
finger. While firm support for the busbar can be provided either by the
spring member or the housing, or both, a problem can arise when the
connector is used with stranded wire. Stranded wire tends to flatten out
or splay when subjected to the compressive force of the spring finger.
Since the compressive and resistive forces of the spring finger are only
created upon deflection of the spring finger, the splaying of the
stranded wire reduces or even eliminates this deflection which can then
defeat the dual purpose of the spring finger. The present invention
addresses this problem.

SUMMARY OF THE INVENTION

[0007]The present invention concerns a push-in wire connector having an
improved busbar which assists in retaining conductors, including stranded
wire, firmly in contact with the busbar.

[0008]A primary object of the invention is a push-in connector busbar
having a surface which restrains conductors positioned thereon.

[0009]Another object of the invention is a push-in connector busbar having
a wire-receiving pocket formed on its wire-engaging surface.

[0010]Another object of the invention is a push-in connector busbar having
a wire-engaging protrusion formed on its wire-engaging surface.

[0011]A further object of the invention is a push-in connector busbar
having both a wire-engaging protrusion and a wire-receiving pocket formed
on its wire-engaging surface.

[0012]Still another object of the invention is a push-in connector busbar
adapted for support on a spring member and having a wire-receiving pocket
opposite a spring finger of the spring member.

[0013]Yet another object of the invention is a push-in connector having a
busbar of the type described which enables the connector to be used on
both solid and stranded wire.

[0014]A still further object of the invention is a push-in connector
having a busbar with a wire-engaging protrusion formed by coining the
busbar.

[0015]An additional object of the invention is a push-in connector busbar
having a wire-receiving pocket on its entry side and a wire-engaging
protrusion on its exit side.

[0016]These and other desired benefits of the invention, including
combinations of features thereof, will become apparent from the following
description. It will be understood, however, that a device could still
appropriate the claimed invention without accomplishing each and every
one of these desired benefits, including those gleaned from the following
description. The appended claims, not these desired benefits, define the
subject matter of the invention.

[0017]These and other objects are realized by a push-in wire connector
having a housing and a busbar in the housing. The busbar has a top
surface with at least two wire-crossing axes. Each wire-crossing axis
intersects at least one of a wire-receiving pocket or a wire-engaging
protrusion. In one embodiment, the wire-crossing axis has both the pocket
and the protrusion, which together provide a serpentine wire path that
enhances the holding power of a spring member.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 is a perspective view of the push-in connector of the present
invention.

[0019]FIG. 2 is a section taken along line 2-2 of FIG. 1.

[0020]FIG. 3 is a perspective view of the spring assembly comprising a
spring member and busbar.

[0021]FIG. 4 is a front elevation view of the spring assembly.

[0022]FIG. 5 is a section taken along line 5-5 of FIG. 4.

[0023]FIG. 6 is a perspective view of the busbar, showing primarily the
top face thereof.

[0024]FIG. 7 is a perspective view of the busbar, showing primarily the
bottom face thereof.

[0025]FIG. 8 is a top plan view of the busbar.

[0026]FIG. 9 is an end elevation view of the busbar.

[0027]FIG. 10 is a bottom plan view of the busbar.

[0028]FIG. 11 is a front elevation view of the busbar.

[0029]FIG. 12 is an enlarged detail view of the portion circled in FIG.
11.

[0030]FIG. 13 is a section taken along line 13-13 of FIG. 8.

[0031]FIG. 14 is an enlarged detail view of the portion circled in FIG.
13.

DETAILED DESCRIPTION OF THE INVENTION

[0032]FIG. 1 illustrates the push-in connector 10 of the present
invention. The push-in connector has a housing shown generally at 12. In
this embodiment the housing is formed in two pieces and includes a
five-sided case 14 and a cap 16. The case has top and bottom walls 18 and
20 joined by left and right side walls 22 and 24. A rear wall 26 closes
the back end of the case. Together the case walls define a generally
hollow interior 28 of the housing. The front side of the case is open to
receive the cap 16. The side walls 22, 24 each have a latch 30, one of
which can be seen in FIG. 1. The latches 30 engage hooks 32 which
protrude from the sides of the cap to retain the cap 16 in the case 14.
As seen in FIGS. 1 and 2, the cap has a plurality of ports 34
therethrough. These ports provide access to the hollow interior 28 of the
case. Partitions as at 36 may be provided in the interior of the housing
to guide the stripped ends of wires as they are inserted into the
housing,

[0033]Turning to FIGS. 3-5 the spring assembly 38 is shown. The spring
assembly comprises a busbar 40 supported on a spring member 42. The
spring member includes a foot 44 joined at a fold line 46 to an
upstanding leg 48. The foot has a pair of apertures (not shown) for
receiving rivets of the busbar as will be described below. The leg 48 is
a sheet divided by slits 50 into three sections 52. The slits 50 extend
from the top edge of the leg and end somewhat short of the fold line 46.
Each section 52 further includes a U-shaped slit 54 which defines a
spring finger 56. The spring finger is integrally connected to its
section 52 at one end 57 and has a free end 58 at its opposite end. As
seen in FIGS. 3 and 5 the spring fingers 56 are bent out of the plane of
the leg 46. The free end 58 may be further angled somewhat relative to
the remainder of the finger to provide an optimum angle for gripping a
wire inserted under the spring finger. The spring member 42 is preferably
formed of a resilient metal such as stainless steel.

[0034]Returning briefly to FIG. 2, it can be seen that the bottom wall 20
of the case 14 cooperates with a lower portion of the cap to support the
foot 44 of the spring member 42. Similarly, interior portions of the cap
engage the leg 46. These cap portions cooperate with the partitions 36 in
the case 14 to restrain the spring assembly 38 in the housing 12. One of
the spring fingers 56 is opposite each of the cap ports 34 so that a wire
inserted into the cap will encounter the spring finger and move it
upwardly as the wire enters the case. The free end of the spring finger
will press on the conductor, preventing it from pulling out of the
housing and pushing it into firm engagement with the busbar 40.

[0035]Turning now to FIGS. 6 and 7, details of the busbar 40 will be
described. The busbar is a generally rectangular member made of
tin-plated copper or other copper alloys, e.g., brass, phosphor bronze or
the like. The busbar defines a thickness T (FIG. 9) between a top face 60
and a bottom face 62. It will be understood that the terms `top` and
`bottom` are used herein for reference purposes only, as there is nothing
inherent in the orientation of the busbar that would make one side or the
other of the busbar a top or bottom portion. In the illustrated
embodiment the top face 60 happens to be exposed to incoming wires while
the bottom face 62 rests on the foot 44, but it could be otherwise. The
busbar 40 further defines an entry edge 64, an exit edge 66, and at least
two wire-crossing axes 68 extending from the entry edge to the exit edge.
As used herein the entry edge will be considered the edge of the busbar
first crossed by a conductor entering the housing and the exit edge will
be considered the edge of the busbar last crossed by an entering
conductor. The wire-crossing axis is the location where a conductor will
lie, given the construction of the housing and the busbar's position
therein.

[0036]The busbar 40 is attached to the foot 44 of the spring member 42 by
means of rivets 70 extending into the apertures of the foot described
above. The rivets 70 on the bottom face 62 may be formed by upsetting a
portion of the busbar, leaving depressions 72 in the top face 60.

[0037]As shown in FIGS. 8-14, the busbar has a wire-receiving pocket 74
extending below the top face 60 on each of the wire-crossing axes 68 and
a wire-engaging protrusion 76 extending above the top face 60 on each of
the wire-crossing axes 68. The protrusion 76 may be formed by coining the
busbar, which creates a depression 78 in the corresponding position on
the bottom face 62 of the busbar. The wire-receiving pocket 72 has a
depth D below the top face of at least about 50% of the thickness T of
the busbar. The wire-receiving pocket has a length L1 of at least about
30% of the distance W between the entry edge and the exit edge of the
busbar. The wire-engaging protrusion 76 has a height H above the top face
of at least about 40% of the thickness T of the busbar. The wire-engaging
protrusion has a length L2 of at least about 50% of the distance W
between the entry edge and the exit edge of the baseplate. It has been
found that these relationships provide suitable constraint on the
conductor while pressed against the busbar. In particular, the depth D of
the wire-receiving pocket must be sufficient to enclose enough of the
sides of a stranded wire to prevent significant splaying of the wire. For
exemplary purposes only and not by way of limitation, for a busbar to be
used on wires sizes 12-18 AWG, T=0.030, W=0.160, D=0.017, L1=0.056,
H=0.012 and L2=0.087, all dimensions in inches.

[0038]It can be seen that the pocket 74 and protrusion 76 form a
serpentine path for the conductor to traverse over the top of the busbar.
This configuration helps the spring finger 56 retain the conductor in the
housing. As mentioned above the pocket 74 surrounds the conductor at
least partially on three sides to prevent splaying of a stranded wire.

[0039]While the preferred form of the invention has been shown and
described herein, it should be realized that there may be many
modifications, substitutions and alterations thereto without departing
from the scope of the following claims. The arrangement of the pocket and
protrusion could be other than as shown. For example, the spring finger
need not be disposed adjacent the entry edge of the busbar. That is, the
busbar could be shifted to the left as seen in FIG. 3. Alternately, or in
combination with such a shift of the busbar position, the wire-engaging
protrusion could be on the entry side and the wire-receiving pocket could
be on the exit side of the busbar. Or the wire-receiving pocket could be
on split into two sections on either side of an intervening protrusion.
Or the wire-receiving pocket could extend all the way across the busbar
from the entry edge to the exit edge with no protrusion Also, while the
connector is shown having three ports and a spring assembly for three
wires, the number of wires which the connector can accommodate could be
other than as shown. Finally, while the dimensions given for illustrative
purposes will accommodate a particular range of wire sizes, other
dimensions could be used to accommodate other ranges of wire sizes.